Chlamydia continues to be a significant pathogen affecting hundreds of millions world-wide. As the etiologic agent of trachoma, C. trachomatis is the most common cause of preventable blindness in the world. However, perhaps the most significant impact of Chlamydia is in its role as the most common bacterial cause of sexually transmitted infection, often leading to pelvic inflammatory disease and subsequent tubal obstruction and infertility in women. In addition, C. pneumoniae is a major cause of community-acquired pneumonia and has been associated with coronary artery disease. In the veterinary world, C. abortus is a significant cause of ovine abortion and has an important economic impact, while the avian pathogen C. psittaci is often associated with potentially severe respiratory zoonotic infection in humans. Current technology, particularly genomics, has resulted in a rapid explosion of new and exciting work in the understanding of the molecular and cellular interactions of chlamydiae with their host cell which impacts the pathogenesis and host response to the infection. The Chlamydia Basic Research Society was founded with the primary goal of providing a forum to address basic research on chlamydiae and chlamydial infections at biennial meetings. Four previous meetings with an average of 240 attendees from as many as 17 countries have convened with outstanding success, and this conference is now viewed by the Chlamydia research community as the main forum for the presentation of new basic research. A major goal of the Society is also to strongly encourage the participation of graduate students and post-doctoral fellows. At the past four meetings, an average of 41.4% of the registrants was graduate students and post-doctoral fellows. This was accomplished by scheduling the conference in mid-size US cities to reduce lodging costs and by supporting the registration fees of the trainees with funds that were raised from outside sources including NIH. Trainees are also given preference for platform presentations. Therefore the specific aims of the 2011 meeting will be 1) to encourage and promote basic research in chlamydial biology and pathogenesis, 2) to provide a forum for the exchange of information among scientists engaged in research on basic chlamydial biology, pathogenesis and vaccine development, and 3) to promote the development of young scientists in Chlamydia research by encouraging their active participation in the meeting. Public Health Relevance: Chlamydia trachomatis is the leading bacterial cause of sexually-transmitted infections with approximately 10% of the sexually active population infected. It is also a leading cause of pelvic inflammatory disease and involuntary infertility in women. A major problem with the disease is that many infections are subclinical and remain undiagnosed, so that major pathologic changes often develop prior to the infection being diagnosed and antibiotic therapy being initiated. Thus there is a strong need for a vaccine to prevent disease. The disease pathogenesis itself is still not completely understood, so basic research on the interaction of the organism with its host cell is essential. The Biennial Meeting of the Chlamydia Basic Research Society addresses these aspects of chlamydial disease but also addresses basic research on other significant infections caused by chlamydiae, including trachoma, pneumonia, and zoonotic infections. Moreover, the emphasis on graduate students and post-doctoral fellows at the meeting is critical for training the next generation of researchers in this field.